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| <concept id="cws" xml:lang="en-us"> |
| <title>Web services overview</title> |
| <shortdesc>A Web service is a set of related application functions that can |
| be programmatically invoked over the Internet. Businesses can dynamically |
| mix and match Web services to perform complex transactions with minimal programming. |
| Web services allow buyers and sellers all over the world to discover each |
| other, connect dynamically, and execute transactions in real time with minimal |
| human interaction.</shortdesc> |
| <conbody> |
| <p>Web services are self-contained, self-describing modular applications that |
| can be published, located, and invoked across the Web.</p> |
| <lq> <p> <uicontrol>Web services are self-contained.</uicontrol> On the client |
| side, no additional software is required. A programming language with |
| XML and HTTP client support is enough to get you started. On the server |
| side, a Web server and servlet engine are required. The client and server |
| can be implemented in different environments. It is possible to Web |
| service enable an existing application without writing a single line of code.</p> <p> <uicontrol>Web |
| services are self-describing.</uicontrol> The client and server need to recognize |
| only the format and content of request and response messages. The definition |
| of the message format travels with the message; no external metadata repositories |
| or code generation tools are required.</p> <p> <uicontrol>Web services are |
| modular.</uicontrol> Simple Web services can be aggregated to form more complex |
| Web services either by using workflow techniques or by calling lower layer |
| Web services from a Web service implementation.</p><p><uicontrol>Web Services |
| are platform independent.</uicontrol> Web services are based on a concise |
| set of open, XML-based standards designed to promote interoperability between |
| a Web service and clients across a variety of computing platforms and programming |
| languages.</p> </lq> |
| <p>Web services might be anything, for example, theatre review articles, weather |
| reports, credit checks, stock quotations, travel advisories, or airline travel |
| reservation processes. Each of these self-contained business services is an |
| application that can easily integrate with other services, from the same or |
| different companies, to create a complete business process. This interoperability |
| allows businesses to dynamically publish, discover, and bind a range of Web |
| services through the Internet.</p> |
| <section><title>Categories of Web services</title><p>Web services can be grouped |
| into three categories:</p><lq> <p> <uicontrol>Business information.</uicontrol> A |
| business shares information with consumers or other businesses. In this case, |
| the business is using Web services to expand its scope. Examples of business |
| informational Web services are news streams, weather reports, or stock quotations.</p> <p> <uicontrol>Business |
| integration.</uicontrol> A business provides transactional, "for fee" services |
| to its customers. In this case, the business becomes part of a global network |
| of value-added suppliers that can be used to conduct commerce. Examples of |
| business integration Web services include bid and auction e-marketplaces, |
| reservation systems, and credit checking.</p> <p> <uicontrol>Business process |
| externalization.</uicontrol> A business differentiates itself from its competition |
| through the creation of a global value chain. In this case, the business uses |
| Web services to dynamically integrate its processes. An example of business |
| process externalization Web services is the associations between different |
| companies to combine manufacturing, assembly, wholesale distribution, and |
| retail sales of a particular product.</p> </lq></section> |
| <section><title>Service roles and interactions</title><p>A network component |
| in a Web Services architecture can play one or more fundamental roles: service |
| provider, service broker, and service client.</p><ul> |
| <li>Service providers create and deploy their Web services and can publish |
| the availability of their WSDL-described services through a service registry, |
| such as a UDDI Business Registry.</li> |
| <li>Service brokers register and categorize published services and provide |
| search services. For example, UDDI acts as a service broker for WSDL-described |
| Web services.</li> |
| <li>Service clients use broker services such as the UDDI Business Registry |
| to discover a needed WSDL-described service and then bind to and call the |
| service provider.</li> |
| </ul><p>Binding involves establishing all environmental prerequisites that |
| are necessary to successfully complete the services. Examples of environmental |
| prerequisites include security, transaction monitoring, and HTTP availability. |
| The relationships between these roles are described in Figure 1.</p><p>Figure |
| 1. Service roles and interactions.</p><p> <image alt="Figure 1 illustrates the interactions between the service broker, service provider, and service requestor." |
| href="../images/roles.gif"></image> </p><p>For more information on Web services, |
| refer to <xref format="html" href="http://www.ibm.com/developerworks/webservices" |
| scope="external">www..com/developerworks/webservices</xref></p></section> |
| </conbody> |
| <related-links> |
| <linklist><title>Related Concepts</title> |
| <link href="cwsinwsa.dita"><linktext>Tools for Web services development</linktext> |
| </link> |
| <link href="cwsstandards.dita" scope="local"><linktext>Web services standards</linktext> |
| </link> |
| </linklist> |
| <linklist><title>Related Tasks</title> |
| <link href="../tasks/toverws.dita" scope="local"><linktext> Developing Web |
| services</linktext></link> |
| </linklist> |
| </related-links> |
| </concept> |
